1. Field of the Invention
This invention relates to the field of semiconductor packaging and has special application to those semiconductor devices such as rectifiers and silicon controlled rectifiers which are designed for relatively high current applications. Such devices are used in assemblies for producing large amounts of DC current from an AC current source and also in those applications where it is necessary to switch on and off relatively large current flows to electrical machinery such as electric motors and the like.
2. Description of the Prior Art
A first general type of prior art packaged semiconductor devices is illustrated in U.S. Pat. Nos. 3,310,716 and 3,443,168. The first-mentioned patent discloses a semiconductor package wherein a wafer assembly comprising a junction member 2 and bracing plates 3 and 4 is disposed between ductile cover plates 6 and 7. Surrounding the periphery of the wafer assembly is an insulating ring 5 which may be composed of sintered aluminum oxide, which ring may be assembled in two halves, as by hard soldering or welding.
The second-mentioned patent discloses a semiconductor package wherein the wafer assembly is disposed between two diaphragm members having flange portions which project outwardly beyond the edges of the wafer assembly. A ring of epoxy resin is molded to these flanges in such a manner as to maintain the diaphragms in compressive electrical contact with the wafer assembly.
U.S. Pat. No. 3,489,957 discloses a commercially available embodiment of a packaged semiconductor. In this embodiment, a semiconductor unit 42 is disposed between relatively massive metal studs 12 and 14. Connected to these studs and encompassing the periphery of the semiconductor unit is a combined ceramic/metallic assembly specially constructed so as to accommodate relative movement within the package.